Elevator control system



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H4, 1 4 1/ B 7 KIT NEY Patented Oct. 15, 1946 UNITED STATES PATENTOFFICE ELEVATOR CONTROL SYSTEM James Dunlop, Ridgewood, N. J., assignor,by mesne assignments, to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Application December 28,1943, Serial No. 515,992

" 39 Claims. (01. 121-41) My invention relates to elevator controlsystems. and more particularly to control systems for elevators in whichhydraulic engines are used for raising and lowering purposes.

One object of my invention is to provide for so controlling the valve ofa hydraulic engine used for operating anelevator as tocause the elevatorto accelerate to a desired speed and then maintain that speed until itnears its stopping point.

A further object of the invention is to provide a hydraulic engine foroperating any suitable apparatus wherein movement of the plunger due toadmission and exhaust of motive liquid is controlled by a valvepositioned by a diflferential responsive to speed of a motor and tospeed of the plunger.

.A further object of the invention is to provide a hydraulic engine foroperating any suitable apparatus by movement of a plunger in consequenceof admission and exhaust of motive liquid controlled by a valvepositioned in response to speed of a motor and to speed of the plungeras well as to the position of the latter.

Another object is to provide a valve control for a hydraulic engine usedin connection with an elevator in which the valve will be operated by amotive means running at a predetermined speed and be controlled by adifferential means responsive to the movement of the elevator and torotation of the valve by its motive means for securing a smooth,constant predetermined movement of the elevator.

Another object is to provide means operated by a hydraulic engine forpositively moving its valve to its stop position as its plungerapproaches the end of its stroke regardless of the operation of themotive means for moving the valve.

Another object is to provide a large valve and a small valve, and meansfor moving the small valve at a speed relative to the speed of the largevalve during a stopping operation which will secure a smooth accuratestop.

Another object is to provide a means for balancing the operation of alarge valve and a small A further object is to provide a valve operat-'ing means for a hydraulic engine with a cam means responsive to themovement of the hydraulic plunger for moving the valve to its stopposition when the plunger approaches closely the end of its stroke andto provide means for adjusting the position of the cam in relation tothe extent of opening of the valve means so that its lift surface may beused substantially to its full extent to move the valve means in aclosing direction. I

A still further object is to provide a valve operating mechanism forhydraulic engines used for hoisting extremely heavy bodies which shallgive smooth and rapid acceleration in starting, a constant speed ofmovement of the body after acceleration is completed, and a smoothdeceleration at the end of the stroke of the engine plunger, with apositive stop as the plunger reaches the end of its stroke.

It is also an object of my invention to provide a valve control systemfor hydraulic engines used in hoisting large bodies which shall besimple and inexpensive to construct, install, operate and maintain inoperation.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which:

Figure 1 is a diagrammatic representation in end elevation of adeck-edge elevator on the side of a ship provided with my improvedhoisting apparatus,

Fig. 2 is a diagrammatic representation, in side elevation, of theelevator illustrated in Fig. 1 as seen from the inside of the ship andlooking outboard and with the elevator platform at the top deck insteadof at the main deck,

Fig. 3 is an enlarged view, in side elevation, of the engine foroperating the elevator illustrated in Figs. 1 and 2 with my improvedengine valve and apparatus for operating it,

Fig. 4 is a view of the engine valve taken on the line IV-IV of Fig. 3showing the engine valve in cross-section,

Fig. 5 is a view taken on the line V-V of Fig. 4, showing the main valveon a by-pass for the oil back of the balancing pistons,

Fig. 5A is an enlarged plan view of one of the ports shown in Figs. 4and 5,

Fig. 6 is a sectional view taken on the line VIVI of Fig. 4 to show theinterior arrangement of the valves, 7

Fig. '7 is a sectional view through the large valve casing taken on theline VIIVII of Fig. 4,

'Fig. 8 is a view taken on the line VIIIVIII of Fig. 3, giving an endview of the valve casing and its location on the engine,

Fig. 9 is atop plan view of the gear reducing mechanism associated withthe engine valve,

Fig. 10 is an enlarged top view of the hand control station for theengine Valve, with the top of its casing removed to show the interiorparts in full lines,

11 is a View, in front elevation of the hand control station with theside of its casing removed,

Fig, 12 is an enlarged top plan view of a portion of the valve operatingmechanism embodying the invention as applied to the engine shown in Fig.3,

Fig. 13 is a view, in side elevation, of the valve operating mechanismillustrated in Fig. 3,

Fig. 14 is an enlarged top plan View of a cam mechanism movable by theengine plunger at the end of its stroke for closing its valve,

Fig. 15 is a view, in side elevation, of the cam mechanism illustratedin Fig. 14,

Fig. 16 is an enlarged cross-section view through the center of a camlocking device on the cam mechanism illustrated in Figs. 14 and 15,

Fig. 171's an enlarged cross-section view through the center of thedifferential housing illustrated in Fig. 3,

Fig. 18 is an enlarged top plan view of the coupling between the T leverand the main valve shaft,

Fig. 19 is a view in cross section of the cou pling in Fig. 18,

Fig. 20 is a view in side elevation of the lever arrangement for closingthe engine valve,

Fig. 21 is a straight-line diagram of the control circuit for the valvemotors,

Fig. 21A is a key representation, showing the location of the relays andtheir contacts in Fig. 20,

Fig. 22 is a view in side elevation of a modified form of my inventionas applied to an elevator in which parts of the engine control areoperated directly by the elevator platform, and

Fig. 23 is a modified form of one of the valve ports shown in Figs. 4and 5.

Although the invention is illustrated in con nection with a hydraulicengine for operating the hoisting cables of large deck-edge elevatorssuch as are used on airplane carrier ships, it is to be understood thatit may be used in controlling the valves of hydraulic engines foroperating elevators of other types or for any other suitable purpose.

Referring more particularly to the drawings, I have illustrated adeck-edge elevator compris ing an elevator platform l0 disposed betweenpair of guide rails II and I: mounted on the outside of a ship hull l3,in position to be supported by and to be raised and lowered between amain deck M and a flight deck l5 by a pin rality of hoisting cables l6and I1 operated by a hoisting engine [8.

The platform It! comprises a base section and a hinged or outboardsection 2!, the floors of which normally lie in the same plane andprovide a large level area upon which airplanes may be moved and carriedfrom one deck to another. The base section of the platform isconstructed with a suitable flooring 22 laid upon a frame 23 made ofseamless steel tubing, structural steel sections and steel plate weldedtogether in bridge-like construction to form a relativeiy lfght butstrong structure. The outboard section of the platform is alsoconstructed with a suitable floor 24 laid upon a frame 25 of scamlesssteel tubing, structural steel and steel plate welded together inbridge-like construction in the same manner as the base and is mountedupon and connected to the base by a suitable ing engine at suchpositions that the 4 hinged joint 25 so that it may be raised from itsnormal horizontal position into a vertical position on the base when theship has to Pass through a canal lock or other narrow opening.

The guide rails ii and 12 are mounted in vertical position and facingeach other on the side of the ship hull by means of a plurality ofhorizontally disposed brackets 28.

The guide rails are provided with vertical slots 29 in their sidesfacing each other which are disposed to receive a plurality of rollers3i rotatably mounted on the base section 20 for the purpose of guidingthe movement of the elevator platform as it is raised or lowered and foraIso maintaining the platform in its horizontal position. A block 32 issecurely fastened by Welding to the lower end of each guide rail toprevent the elevator from dropping on down through the slots in case offailure of the safeties, cables, etc. In normal operation, the platformis suspended entirely by its hoisting cables.

The hoisting en ine i8 operatively connected to the platform to raiseand lower the latter. As shown, the hoisting engine I8 is a hydraulicengine comprising a cylinder 34 mounted in a horizontal position on aframe or engine bed 35 and a power plunger 36 disposed in the cylinder.The outer end of the plunger is provided with a power head 31 in which apair of power sheaves are rotatabiy mounted. The plunger in the cylinderslides back and forth horizontally and thus moves the power sheaves backand forth with it. Guide rails :35 and 43a are mounted on the sides ofthe engine frame 35in position to extend into grooved guide lates 39 and39a (Figs. 3 and 8) on the sides of the plunger head for supporting theouter end of the plunger in its horizontal movements. Suitable stoppingblocks such as 4| and 5| (Fig. 2) are provided for stopping the plungerat the end of its forward stroke and at the end of its rearward stroke.

Suitable stops lg (Fig. 1) are mounted on the flight deck to stop theplatform thereat and by placing the plunger stops 4| and 51 on thehoistengine will continue the hoisting pull on the cables after theplatform is stopped by the stops l9 until all of the stretch in thecables is taken up, the platform will be held level with the flight deckwhen stopped thereat regardless of loading. For more detailedinformation on the means for holding the platform at the flight deck,reference may be had to my copending application No. 597,132, filedOctober 21, 1943, in which such means are described and claimed.

The plunger is designed for operation by any suitable hydraulic mediumsuch as oil maintained under pressure by any suitable pumping apparatus(not shown).

A valve block 42 is mounted on the cylinder for controlling theoperation of the plunger by opening an oil pressure port 43 from a highpressure tank (not shown) for raising the platform and by opening an oilexhaust port 4-1 to a low pressure tank (not shown). The low pressuretank and the high pressure tank are not shown because they are old andWell known in hydraulic engine systems for providing a closed systemhaving a low pressure side and a high pressure side.

The hoisting cables it} at the 1eft-hand end of Lie platform are securedto the base 23 by means of a bracket 415 mounted thereon and passupwardly and over an idler sheave 46 fastened to the ship structureunderneath the overhanging portion of the flight deck, thence reanvardlyover a second idler sheave 41 mounted on the ship frame inside the hull,thence downwardly and under a deflector sheave 48 mounted on the enginebed 35, thence around a stationary sheave 49 mounted on the engine bed,thence forward and around one of the power sheaves 38 mounted in thepower head 31, and thence to a dead-end hitch 50 mounted on the lowerpart of the rear end of the engine cylinder 34.

The hoisting cables ll at the right-hand end of the elevator are securedto the base 20 by a bracket 52 mounted thereon and pass upwardly andover an idler sheave 53 fastened to the ship structure underneath theoverhanging portion of the fight deck, thence rearwardly over a secondidler sheave 54 mounted on the ship frame inside the hull, thencedownward and under a deflector sheave 55 mounted on the'engine bed,thence under and over one of the power sheaves 33 mounted in the engineplunger head 37, and thence to a dead-end hitch 56 mounted on the upperpart of the rear end of the engine cylinder,

The valve block 42 is provided with a main valve 68 and a leveling orvernier valve 6! (Fig. 6) for controlling the flow of oil into theengine cylinder through the high pressure port 43 and a cylinder port 32and out of the cylinder through the cylinder port and into the lowpressure port 44.

The main valve 80 is preferably cylindrical in form and is operated by ashaft 63 which is slidably and rotatably mounted in a valve chamber 64by means of a pair of stuffing box glands 65 and 65 which close theouter ends of the valve chamber.

The pressure port 43 is connected with the section 64a of the valvechamber 64. The exhaust port 44 is connected to the section 64b of thevalve chamber. The valve chamber is connected at its central sectionwith the cylinder port 62 by a plurality of valve ports 640.

The valve ports 640 are provided with tapering ends GM to taper off thevolume of the oil when the valve is closing, and to prevent excessiveleakage through the port when the valve is closed,

as a longer lap is provided than in other types.

The form of these valve ports prevents water hammer and vibration, oftenresulting with the use of other ports in systems similar to this.Furthermore the tapered ports will cause the engine to operate moresmoothly than with the ports usually used. Tapering of the port endsprovides for increase in flow area at an increasing rate in relation tovalve travel as the valve uncovers its cylinder port, with the resultthat the desired acceleration for starting may be had in order that theelevator may be rapidly brought up to the speed determined by that ofthe motor means. While tapering of the port ends inherently involves adecreasing rate of flow area decrease in relation to valve travel andwould unduly string out deceleration due to movement of the valve inresponse to differential action in proached without shock or hammeringand with smooth operation. Hence, with both acceleration anddeceleration rapidly and smoothly effected, the elevator may move atmaximum speed for the maximum portion of the travel distance.

With the valve 60 lappingthe ports 640, Oil

cannot flow through the latter into or out of the engine cylinder. Thevalve has suflicient axial length to cover the ports 640 as soon as itapproaches closely to its dead-center position so that it will lap suchports while the vernier or leveling valve 6! is still slightly open. Ifthe valve 69 is moved toward the port 44 so as to uncover the ports 640,then (Fig. 7) oil flows through the high pressure port 43, the valvechamber section 64a, the valve ports 64c and the cylinder port 62 intothe engine cylinder; and, if the valve is moved from its dead centerposition in the other direction toward the port 43, then oil flows outof the engine cylinder through the cylinder port 62, the valve ports64c, the valve chamber section 64b and the low pressure port 44.

It will also be apparent that with the tapered valve ports, the relativelapping of the valves and the leverage, the opening and closing of theengine ports will be progressive for the purposes indicated.

A pair of balancing, pistons 61 and B8 are also mounted on the shaft 63in the outer portions of the valve chamber and an equalizing passagewayll (Fig. 5) connects passages 69 and 10 connected with the valve chambersections back of these pistons. The passageway H is also connected by apassageway 72 with the low pressure or exhaust port 44. The equalizingpassageway and the balancing pistons provide means for minimizing theoil leakage from the high pressure side of the system. The equalizingpassage keeps the same pressure on the two ends of the valve to keep thesystem in balance statically and permit ready movement of the pistons.Movement of the pistons will cause oil to flow through the equalizingpassage; and, if the passage is restricted, a load is placed on thevalve drive. This load slows down the valve drive motors (to bedescribed later herein). Therefore, a screw threaded valve lid ismounted in the equalizing passageway for adjustably restricting the flowof oil through the passageway and thus secure better control of theacceleration and retarding action of the motors.

While the shaft 63 may be operatively connected to the main valve in anysuitable manner, preferably, as shown, such shaft carries the mainpiston valve 60 and the balancing pistons 61 and 68 to constitute apiston valve structure rotatable in the cylindrical valve chamber.Therefore, the 'term valve shaft, as used herein, has the significanceof a shaft capable of positioning a valve of any suitable type whetherthe latter is unitary with the shaft or operated by the latter.

The leveling or vernier valve 6! is preferably made as a piston portionon a leveling or vernier valve shaft 13 slidably disposed in a verniervalve chamber 14 in the valve block and disposed parallel to the mainvalve chamber 64. The ends of the leveling or vernier valve chamber areclosed by a pair of stuffing box glands 15 and 1B. The high pressureport or space 43 is extended at 43a to communicate with a plurality ofports 14a in the leveling valve chamber 14 and the cylinder port 62 isextended at passage 62a to communicate with a small valve port 14b inthe central portion of the leveling valve chamber. The low pressure portor space 44 is extended at 44a to communicate with one or more ports [40in the leveling valve chamber.

The leveling valve Si is closed when it is in it central position andcovering the port 14b, as

shown in Fig. 6-, and no oil can then flow through such port into or outof the cylinder. When the leveling valve GI is moved to the left, itadmits 'oil from the high pressure port 43 through the extension 43a ofthe latter and the ports 14a and 141) into the cylinder port leadinginto the engine cylinder. When the valve BI is moved to the right, itpermits oil to flow out of the engine cylinder and the cylinder port andthrough the ports Nb and He and the passage Ma into the low pressureport 44.

The shaft 63 of the main valve is connected to the shaft 13 of theleveling valve by a lever or other mechanism 11 (Figs. 3 and 20) so thatmovement of the main valve moves the leveling valve. The lower end ofthe lever 11 is fulcrumed on the engine frame 35 by a link Tia, itscentral portion is connected to the shaft 63 by a swivel coupling 18 andits upper end is connected to the shaft I3 by a link 110. An adjustablejoint 11d (Figs. 3 and 20) is used to connect the link 110 to the shaft13 so that the position of the leveling valve relative to the positionof the main valve may be readily adjusted.

The link 11a (Fig. 2-0) is preferably adjustably connected at He and 71bto the engine frame 35 and to the lever 11 to vary the lever arms withrespect to the valves so that the travel of the leveling valve may beadjusted for a given stroke of the main valve.

The coupling 18 (Figs. 3, 18 and 19) is pivotally connected to the shaft63 by means of a combined radial and thrust ball bearing 19a (Figs. 18and 19) held by a cap 78b in a body 180 which is mounted by trunnionpins in the forked right end of the coupling.

The main valve 60 is arranged to lap its ports 640 to a greater extentthan the leveling valve 14 covers its ports Mb with the result that theports 640 are closed with the leveling valve ports 14b partially open.Due to the tapering of the ends of the main valve ports 640, to theadjustment of the main and Vernier valves, and to the shape of theactuating cam (hereinafter described), the main and leveling valves aremoved in closing and opening directions to provide a metering or verniereffect, thereby securing a restricted or graduated inflow or outflow ofoil with consequent smoothness of action. Further, with the valve piston69 lapping its cylinder port Me, the Vernier valve partially covers itscylinder port 14b so that high pressure is effective to hold theplatform in its up position and so that liquid under low pressure actson the plunger to counteract the effective gravity to a desired extentwith the platform in its lowermost position.

The means for operating and controlling the main valve comprises (Fig.3) a pair of motors 80 and BI responsive to a push button control systemfor rotating the valve-positioning shaft 63, a gear mechanism 82operated by the engine plunger, a differential mechanism 83 responsiveto operation of the valve-positioning shaft and the gear mechanism forautomatically controlling movement of the valve to secure the desiredacceleration and normal running speed of the elevator, and cammechanisms 84 and 85 for effecting valve-closing movement upon thecompletion of a plunger stroke, the cam mechanism 84 being moved intooperating position by the plunger at the end of its inward stroke, andthe cam mechanism 85 being moved into operating position by the plungerat the end of its outward stroke.

The motors 80 and 8| may be reversible constant speed torque motors ofany suitable type mounted by a base plate 86 on the engine bed 35 andconnected to the main valve shaft 83 by a slidable gear reducingmechanism Bl. The motors should be so constructed that they can bestalled and even reversed in motion by a forcible closing movement ofthe valve during a valve closing action as the plunger reaches the endof either its forward stroke or its rearward stroke. It will be obviousthat one motor instead of two motors may be used where desirable.

The gear reducing mechanism 81 (Fig. 9) is provided with a casing 88 inwhich the right-hand end of the valve shaft 63 is rotatably mounted.Inasmuch as the shaft 53 moves longitudinally, a cap 89 is mounted onone side of the casing to protect the outer end of the shaft when itmoves beyond the casing wall. The motors 90 and BI are coupled on ashaft which extends into the casing 88 and is provided with a pinion 9|disposed to mesh with a gear wheel 92 fixed on a gear shaft 93 rotatablymounted in the casing. A pinion 94 is disposed on the gear shaft inposition to mesh with a gear wheel 95 mounted on the valve shaft 63 sothat rotation of the motors will effect a corresponding reduced rotationof the valve shaft. The pinion 94 is made much wider than the gear wheel95 so that the shaft 63 may move axially with the gears still in mesh.

A clutch or power transmitting device 95a (Fig. 9) is disposed betweenthe gear wheel 95 and the shaft 63 and provided with spring connectors95b to permit a limited resilient axial movement between the gear wheeland the shaft sufficient to absorb shocks between the gear and the shaftand also to take care of the rotational movement of the shaft during thefinal closing movement of the cam mechanism after the motors aredeenergized and a brake I99 is applied. Any suitable clutch or resilientpower transmitting device which will permit a limited axial movement ofthe shaft may be used but I prefer to use the power transmitting devicedisclosed and claimed in my copending application Serial No. 514,519,filed December 16, 1943.

The shaft 63 extends through the differential mechanism 83. A portion ofthe shaft 63 in the differential is formed as a screw I96 having a.steep pitch to constitute one part of the differential (Fig. 17). Theother part of the differential is constituted by a nut member IEII whichengages the screw I99 and which is capable only of rotational movementcontrolled by the engine plunger.

The threads of the screw and of the nut are coarse and have such helicalangles that either may drive the other by screw-and-nut action. Hence,if the screw and the nut have differential rotation with the nutrestrained against axial movement, the screw-threaded action will givean axial movement to the valve-positioning shaft for moving the valvemeans in opening and closing directions.

With the nut capable only of rotational movement and the screw arrangedboth for movement rotationally and translatorily in an axial direction,it will be apparent that these parts are capable of functioning as adifferential. The effect of rotary input motion or motions imparted tothe screw and/or nut is to give to the screw a translatory output motionprovided that the screw and nut rotate differentially, the effect ofrotary input motion given to the screw being to move it translatorily tomove the valve means in an opening direction and the effect of rotaryinput motion given to the nut being to move the screw translatorily tomove the valve means in a closing direction.

Furthermore, the screw has a thread of such angle that it is notself-locking but is a free-running screw so that it may have translatoryinput motion imparted to it in response to plunger position, in whichevent it will have a rotational output motion unless the nut is rotatedsufficiently to avoid the latter. Therefore, it is essential thatrotational movement of the shaft 63 for this reason shall not beprevented or resisted unduly. Hence, the driving motor has a rotor whichis freely rotatable relative to its stator structure so that therotational effort of the shaft may retard or reverse the rotor. Also,because of such rotational output motion of the shaft 63, the gear 95 isconnected thereto by the resilient coupling 95a providing for a limitedrelative angular movement of the shaft 63 when such gear is held by thebrake, such coupling being disclosed and claimed in my aforesaidapplication, Serial No. 514,519.

From the foregoing, it will be apparent that the screw may have appliedthereto either rotational or translatory input motion, that the nut hasonly rotary input motion imparted thereto, and that in all cases outputmotion of the differential is delivered by the screw, such output motioneither being translatory motion of the screw or rotational movementthereof depending, respectively, on rotary input motion and translatoryinput motion being imparted thereto.

Inasmuch as the pinion 04 is much wider than the gear wheel 95 and has awidth equal to the length of the screw I03 of the differential, theshaft 63 and the gear wheel 95 are permitted to move axially a distanceequal tothe width of the gear pinion 94, which distance should be equalto the distance the shaft must be moved to open and close the valveports.

The differential mechanism 83 is disposed in a gear casing I (Fig, 1'?)mounted on the engine. The nut IOI has an extended hollow shaft orsleeve portion IOIa and is rotatably mounted in the casing by a pair ofball bearings I04 and I05 which prevent axial movement thereof butrender it easily rotatable. The means by which the plunger rotates thenut comprises a bevel gear I02 fixed on the nut, a bevel gear I03disposed in mesh with the bevel gear I02 and fixed on the lower end of avertical shaft I08 rotatably mounted in the upper part of the casing bysuitable ball bearings I09 and H0, and a gear wheel III fixed on theupper end of the shaft in position to be operated by the gear mechanism82 operated by the plunger.

The gear mechanism 82 includes a gear wheel I II which is fixed on theupper end of the shaft I08 in position to be engaged by and operated bya gear rack II2 (Figs. 12 and 13). The gear rack H2 is fixed on a rackbar II3 slidably disposed between and support-ed by a plurality ofrollers I I4 in a plurality of brackets I I5 mounted on the engine bed.An arm H6 is mounted on the plunger head with its upper end attached tothe rack rail so that the plunger will move the rack rail along with itas it moves back and forth and thereby cause rotation of the gear wheelIII, shaft I 08, gear wheel I03 and gear wheel I02.

Inasmuch as the gear wheel I02 is fixed on the nut I 0! which isrestrained from axial movement and which is disposed on the screw I06 onthe valve shaft 63, rotation of the gear wheel I02 will cause eithersimilar rotation of the Valve 1'0 shaft 63 or axial movement thereof,depending upon whether or not the valve shaft is being rotated at thetime and its speed of rotation. When .the shaft 63 is rotated by themotors and 8| it will move axially if the bevel gear wheel 502 isstationary.

With this construction, when the plunger and the nut IOI are at rest andthe motors 80 and 8| are operated to open the main valve to its upposition or to its down position, they rotate the valve shaft 63 in thenut I0 I. This rotation of the shaft and its screw I 06 causes axialmovement of the shaft and the valve as long as the nut I 0| remainsstationary; but, as the plunger starts to move, it rotates the nut I 0|on the screw threaded portion I06 of the shaft 03 and thereby slows downthe axial movement of the shaft.

As the plunger speeds up, the rotational speeds of the nut IOI and theshaft 63 approach each other, and, at the desired speed of the plunger,the speed of the nut and the speed of the shaft are the same, so thatthe axial movement of the shaft ceases and the valve remains stationaryin the position to which it has been moved. In other words, the motortends to open the valve while the plunger motion tends to close thevalve. Conse uently, the valve will seek a position which will maintainthe plunger speed in a direct ratio with the motor speed while theelevator is running between terminals. Further, as the valve flow areaincreases until the platform speed is in predetermined relation to themotor speed, it will be apparent that load variations, including thatdue to changes in motive oil viscosity, are cared for by variation inflow area.

The cam mechanism 04 at the left-hand end of the plunger has a rear camII1 (Figs. 12, 13, 14, 15) which is pivotally mounted at its lefthandend by pin I I8 on the rear face on the lefthand end of the rack rail(Figs. 3, 12, 13), so that it will move with the rackrail. Anadjustable' stop bolt H0 in the left-hand end of the cam is disposed toengage a brarket I20 on'the rack rail H3 to limit the up movement of thefree end of the cam. A bolt I2I is mounted on the left-hand end of thecam and passes through a bracket I20 on the rack rail for holding aspring I22 under compression to bias the free end of the cam upwardly tothe limit set by the stop bolt II 9. The upper face of the cam II! isdisposed to engage and raise a roller I23 on the left arm I24 of aT-lever I25 when the rack rail is moved by the engine plunger to theright as it approaches the end of its inward stroke.

The T-lever is rotatably mounted in a pair of bearings I26 and I2! onthe engine frame and is also provided with a right-hand arm I28 carryinga roller I29 disposed to be engaged by a front cam I30 in the cammechanism at the rear end of the plunger. The cam I30 is mounted on theright-hand end of the rack rail in the same manner as the left-end camII! but in reverse relation with respect to the latter.

The shape of the upper face of the cam II! is such that it willgradually raise the roller I23 as the plunger approaches the end of itsrear stroke and thereby rock the T-lever in clockwise direction. Theshape of the cam I30 is such that it will gradually raise the roller I29when the engine plunger approaches the end of its forward stroke andthereby rock the T-lever in counterclockwise direction. The shapes ofthe cams will usually be slightly different in order to secure the mostdesirable slowdown effects as the plunger approaches the end of itsoutward stroke and as it approaches the end of its inward stroke. Camtips I3I and I32 are mounted on the cams Ill and I30 for ensuring thepredetermined closing movement of the valve desired at the end of eitherplunger stroke. These tips are preferably removable so that they may bereplaced at any time when worn or when it is desired to change thecontour of the cams at their valve closing points. As the cams arebiased upwardly about the pivots IIB by the springs I22, they arepositioned to be acted upon by the follower mechanism, each cam therebybeing positioned to suit the extent of valve opening. As the cams arethen looked in adjusted position, it will be apparent that the surfaceof each cam will be effective to its full extent regardless of variationin lift occasioned by the extent of valve opening variation with theresult that the closing action begins approximately at the same point inthe elevator travel under different conditions.

The T-lever I is provided with a depending arm I33, the lower end ofwhich is pivotally connected to the swivel coupling I8 on the left endof the valve shaft 63.

Inasmuch as the swivel coupling I8 connects the T-arm I33, the lever 11and the shaft 63, any movement of the T-lever by the cams will effectaxial movement of the shaft 63 and the shaft I3. Conversely, any axialmovement of the shaft 63 will move the T-lever and the shaft 13.

By reason of the leverage exerted by the lever 11, the shape of thevalve-closing cams, the larger lap of the main valve as compared to thevemier valve as well as the lapping relation of the valves, the offposition of the valves at the end of up travel will not be the same astheir off position at the end of down travel. The shape of the up cam Ishould be such as to operate the T-lever to so move the valves that,while the main valve is closed, the leveling or Vernier valve will leavea little of the leveling port exposed when the plunger is forced againstits up stopping blocks 4| and thereby keep the plunger forced againstthem with full pressure on up motion due to the leakage through theexposed portion of the up leveling valve permitting pressure from thepressure side of the system to build up.

On the other hand, on down motion the weight of the platform is keptfrom causing too rapid speed of the plunger for the down direction bybalancing part of the weight by the pressure in the low pressure side ofthe system, as the cylinder is exhausted to the low pressure tank. Atthe lower level, the cam closes the ports in the main valve and in theleveling valve until the reduced rate of the exhausting oil slows downthe platform. Finally the plunger strikes its rear stop, but the shapeof the down cam H1 is such that it does not cause the leveling valve tofully close the leveling valve port but leaves a little of it exposed sothat the remaining pressure in the cylinder causes the oil to leak outuntil the pressure in the cylinder equals the pressure of the lowpressure side of the system. Consequently, a considerable part of theplatform weight and load is absorbed in pressing the plunger against itsrear stop.

If an emergency stop is made between the landings, the main valve andthe leveling valve will be moved to their dead center position toprevent creepage of the plunger to either terminal under leakage throughthe leveling port, The

cams move the valves at the terminals but the rack gear II?! on theplunger acting through the differential moves the main valve andconsequcntl'y the leveling valve in an emergency stop and the fartherthe creep the greater the motion to move the valves to their dead centeror no creep position. Hence in an emergency stop, the cylinder port willbe completely closed and no oil will enter or leave the cylinder, thuscausing the plunger and the platform to remain stationary.

The stopping cam Ill has been described as a floating cam with a springI22 for biasing it upwardly to the limit set by its limit bolt H9, andin order to make it effectively operate the arm I24 of the T-lever, itsfree end must be locked or bolted to the rack rail at the time it startsits decelerating and stopping operation. It is feasible in many cases touse ordinary bolting means for fastening the cam permanently to the rackrail, but inasmuch as there are times when the viscosity of the oil orvariations in the loads may cause the T-arm I24 to be out of its normalposition at the time it meets cam at the start of a valve closingaction, Therefore in order to render the cam effective at whateverheight best suits the position of the arm I2! under prevailingconditions, I have provided a cam lock MI which is responsive to theposition of the plunger for locking the cam I I1 against the rack bar inwhatever position it may be in at that time and holding it there untilthe valve closing action is completed.

The cam lock I4I (Figs. i l, 15, 16) has a locking block I42 welded orotherwise secured to the rack bar II3 and provided with upwardlyextending teeth disposed in its side to be engaged by cooperatingdownwardly extending teeth in a latch I43 movably mounted by a shaft M4disposed in a support member I49 in the cam H1. The shaft I44 isretained in the cam I H by means of a bolt I45 which passes through acap holder hi6 mounted on the outer end of the shaft.

The latch block I43 is biased away from the lock block I42 by a springI47 mounted on the shaft I44 between a shoulder I48 on the seatingmember I43 and the inner edges of the cap I46. A biasing spring I56 isalso disposed around the bolt I45 between the inner portion of the shaftHi l and the inner portion of the cap 246. The use of the two springsprovides a resiliently controlled means for biasing the locking latchaway from the locking block and for permitting a soft and easyengagement therewith. A pair of guide blocks I5I and I52 are mounted onthe cam II? at each side of the locking latch I43 for the purpose ofmaintaining the latch in vertical position.

Any suitable means may be provided for causing operation of the lockinglatch such a stationary cam I54 mounted on a part I55 of the engineframe in position to engage a roller I56 mounted in a lever i5? forlocking the look as the plunger approaches the end of its rearwardstroke. The base end of the lever IE1 is mounted on a base support I53attached to the racl: rail. H3 and its other end is disposed inengagement with the outer end of the cap I45 on the cam locking device.As shown in Figs. 4 and B, when the plunger approaches closely the endof its rear stroke, it will move the lever I51 and its roller I56 intoengagement with the cam I54, thereby forcing the lever I5"! against theouter end of the locking latch to move it against the locking block andthereby lock the cam II'I against any further downward movement, so thatthe cam I I1 will present a firmly supported face to the roller I23 andthus operate the T-arm I24 to accurately slow down the plunger and shut.the valve completely at the end of the rear stroke of the plunger. Asimilar lock operated in a similar manner by the cam IBM; is alsoprovided for the front cam I30.

Inasmuch as the valve shaft 63 extends from the valve block through thedifferential mechanism and the gear reducing mechanism, it isconstructed in sections connected by a plurality of universal joints I53to relieve any strain which may be incurred by the length of the shaftor misalinement of any parts with which it is associated.

The control system diagrammatically illustrated in Fig. for controllingthe valve motors to cause automatic operation of the elevator, includesthe following relays and contactors:

SIIU, Up direction relay,

80D, Down direction relay.

U, Up direction contactor.

D, Down direction contactor.

6, Contactor for motor 8I.

SR, Running relay.

TR, Contactor for shorting resistance in primary motor 80.

IRU, Initial limit switch up direction.

ZRU, Follow up limit switch up direction.

Final limit switch up direction.

IRD, Initial limit switch down direction.

2RD, Follow up limit switch down direction.

3RD, Final limit switch down direction.

80, Starting and running motor (drives valve open).

ilI, Running motor (direct coupled to motor 80).

An up push button U13 and a down push button DB are provided forenergizing the direction relays to cause operation of the elevator inthe up or the down direction, and an emergency stop button SB isprovided for deenergizing them to stop the platform at any time. Thesepush buttons should be located at some convenient station for operationby an attendant.

The up push button controls an up direction relay SIIU and the down pushbutton controls a down direction relay 801) which, in turn, control anup direction contactor U and a down direction contactor D for connectingthe valve motor 80 to three alternating current supply conductors I, IIand III and for preparing the circuit of the valve motor 8! foroperation.

The running relay SR is connected across two of the conductors for themotor 80 so that it will be energized when the motor is energized. It isprovided for the purpose of preparing the circuits of the contactor 6and the contactor TR for operation.

The contactor 6 is responsive to operation of eitherone of the directionrelays and the running relay and is provided for energizing the motor 8|after the motor 80 is energized. The shunt- 7 ing contactor TB, isresponsive to energization of either one of the direction relays and therunning relay and is provided for short-circuiting a plurality ofresistors rI T2 and T3 in the circuit of the motor 80.

The initial limit switch IRU, the follow-up limit switch ZRU and thefinal limit switch 3RU for the up direction are electrically connectedin the control circuit and mounted on the engine frame (Fig. 13) inposition to be operated by a cam I8I attached to the engine plunger asthe engine moves to the end of its forward stroke. Simi- 14 larly, theinitial limit switch IRD, the follow-up limit switch 2RD and the finallimit switch 3RD for the down direction are mounted on the engine frame35 in position to be engaged by the cam I8I as the engine plunger nearsthe end of its rearward stroke.

In order to prevent operation of the valve motor control system untilthe other apparatus associated with the elevator is in condition formovement of the elevator platform, the circuit leading to the controlcontactors is provided with a pair of pump interlocks PI and P2, ahand-drive interlock I85, a broken-rope interlock BR, a platforminterlock PF and a pair of stowing guide interlocks SI and $2. One ofthe pump interlocks and all the other interlocks must be in closedposition before the control system can be operated to energize the valvemotors to move the elevator.

At times it may be desirable to operate the engine valve by manual meansinstead of by the motors and their push button control system. ThereforeI have provided a hand drive I59 (Figs. 10 and 11) which may be usedinstead of the motors and their push button control.

The motor drive is used for automatically operating the valve by up anddown push buttons during normal operation and the hand drive is used foroperating the valves by hand when the elevator is being stored or inchedinto any position or in case of failure of the motors or the power towhich the motors are connected. The hand drive is much slower inoperation than the motor drive and is seldom used, but either drive maybe used as a motive means for operating the valve shaft 63.-

The hand drive I59 (Figs. 3, 9, 10 and 11) is mounted in a casing orstation I50a, embodying hand-operated mechanism for operating a shaftI60, the lower end of which is connected by a pair of beveled gears ISIand I 62 to the gear pinion 94 in the gear reducing mechanism 81 fordriving the gear wheel to rotate the main valve shaft 53.

The upper end of the operating shaft ISO is rotatably mounted in thecasing I 59a and a beveled gear IE3 is mounted on its inner end inposition to be engaged by cooperating beveled gear I64 slidably fixed ona gear shaft I65 rotatably and slidably mounted in the central portionof the casing I59a by shaft supports I659, and IBM). A hand wheel I65 ismounted on the outer end of the shaft I65 for use in rotating it. Inorder to provide for easy rotation of the hand wheel and the shaft, acrank arm I61, having a handle I68, is mounted on the hand wheel by ahinge joint I69 in position to rotate the hand wheel and shaft when itis moved to its outermost position. A manually releasable springoperated snap latch I19 holds the crank arm in its outer position whenit is ready for operation by hand. A detent III is provided forreleasably retaining the handle in its inoperative position.

A cover I12, connected to the casing I59a by a hinged joint connection I13, is provided for covering the hand Wheel and its crank arm when theyare not in use and for preventing energization of the motors while thehand drive is in use. A latch I 14 is mounted in the casing I59a forlatching the cover I12 in its closed position. This latch may bereleased when it is desired to open the cover, by operating a handle I15which rotates a cam I16 to free the latch.

The cover I12 is pivotally connected by a link I11 to a lever I18fulcrumed on a projection I19 on the right side of the casing (Fig. 11).The free forked end of the lever I18 is disposed in a spool, I83 fixedon the rear end or" the shaft I so that an opening movement of the doorwill operate the lever 11s to move the shaft I65 to the left and therebymesh the gear wheel I54 with the gear wheel I63 to provide for rotationof the operating shaft I when the crank arm I6? is rotated. Thismovement of the gear shaft I moves the hand wheel I65 and its operatingcrank arm I6! outwardly so that they may be easily operated. A springIE2 is mounted on the shaft I65 between the spool um and a collar 583 tosoften the engagement of the gear IG- l with the gear I63 when they aremoved into engagement with each other.

The shaft IE5 is provided with a spool-like por tion I84 near itscentral portion disposed to receive the forked end of a lever liltforoperating an interlock switch I85 mounted on the inner side of thecasing I59a. When the gear shaft I65 is moved to the left to engage thegear I64 with the gear I63 for hand operation, it moves the lever I85 toopen the switch I35 in the control circuit for the valve motors 8G and(SI (Fig. 20). When the gear I64 is disengaged from the gear I63, themovement causes the shaft to move the lever I85 to close the switch .36so that the valve motors may be safely operated to move the main valvewhen the hand drive is not in use.

An electromechanical brake I9!) is provided for absorbing the storedenergy of the valve motors and BI when they are deenergized. If nobrakes were used, the coast of the motors in slow- Ing down wouldunnecessarily drag out the retardation of the platform. The brake I58comprises a pair of brake ams l9! and I92 pivotally mounted onprojections I93 on the inner side of the casing ISt'a to extend aroundand embrace a brake drum Hi4 formed on the skirt of the gear wheel I63.The brake arms are biased into engagement with the brake drum by a pairof brake springs I95 and I95 which are held in compression against theouter ends of the brake arms by a bolt I91. The bolt I91 passes throughthe brake to hold the springs against them by a pair of washers I98 andI99. Thus the brake levers, under the force of the brake springs, willapply sufficient force to the brake drum to lock rotation of theoperatin shaft I60, but a resilient connection provided by springs b(Fig. 9) in the clutch 35a permits a small additional rotation of shaft53. My aforementioned copending application Serial No. 514,519,discloses such a construction more fully.

The means for releasing the brake comprises a wedge 2G0 disposed toenter between the outer ends of the brake arms and force them apart. Theouter ends of the brake arms are provided with rol'ers MI t reduce thefriction between the wedging faces of the wedge and the ends of thebrake levers as the wedge is forced between thorn to separate them. Thewedge is adjustably mounted by a bolt 263 on an operating shaft 294, theupper end of which is slidably disposed in a uide projection 285 on theinner top surface of the housing I59a. The lower end of the wedge shaft264 is pivotally connected to one end of a bell crank lever ZilB,mounted by a pivot pin 20'! on the side of the casin ISM. The other endof the bell crank lever is pivotally connected by link 2938 to thearmature 209 of an electromagnet 2H! mounted on the interior of thecasing [59a by a plurality of bolts 2| I. The electromagnet is providedwith a coil 2I2, the terminals of which are connected across two of thesupply conductors for the valve motor 86 so that ener gization of thevalve motor 88 will energize the coil ill! for pulling the wedge 269downwardly into its brake releasing position and thus permit the shaftI50 to rotate with the valve shaft when it is being operated by thevalve motors instead of by the hand drive.

As shown, the brake IE3 is released whenever the valve motors areenergized to operate the valve shaft and is applied to its brake drumwhenever the valve motors are deenergized, to prevent the valve shaftfrom being rotated by the tendency of the valve motors to coast afterbeing deenergized.

t is necessary also to release the brake I90 when the valve shaft isbeing operated by the hand drive. This is accomplished by providing alever arm 2H1 on the bell crank to extend into a lost motion connection2I5 with the link I'I'I leading from the cover to the gear shiftinglever H8. The lost motion connection El is so disposed on the link IIIthat the bell crank lever be moved to brake releasing position by theelectromagnet 2H) without moving, the link ill, but if the door or coverI'IZ is opened, its opening movement will push the link I'I'I to theright and thereby move the bell crank arm BM in anticlockwise direction(Fig. 11) to pull downwardly on the arm 296 and thereby pull the wedgebetween the outer ends of the brake arms ml and IJE to spread them apartand thereby release the brake.

By the foregoing construction, it will be evident that the brake I9!)will be applied to the shaft to prevent rotation of the valve shaft 63only when the hand drive cover I72 is closed, to prevent operation ofthe hand mechanism, and the valve motors are in dcenergized condition,that is, whenever the cover is opened, the brake is releasedmechanically; and, with the cover closed, the brake is released when themotors are energized.

Assumed operation of the apparatus Assuming that the elevator platformIt is at the main deck I4 and ready for movement up to the flight deckI5, that the hand drive cover H2 is closed so that the system i subjectto operation by motor control, that the interlocks including the pumpinterlocks PI and P2 are closed, and that it is desired to move theplatform upwardly to the flight deck, the attendant presses the up pushbutton UB at the control station.

The closed button UB energ zes the up direction relay Bill] by thecircuit LI, PI, I85, BR, PF, S22, SI, SB, UB, SUU, BQDI, BRU, L3, tocause energization of the valve motors. The energized relay EiGU closesits contacts till) i, BOUT and BOU I and opens its back contact 363112.The closed contacts 3;.U3 provide a self holding circuit for the relay.The closed contacts 81lU4 prepare a circuit for the contactor B and theshorting relay TR. The closed contacts BEUl energize the up directionrelay by the circuit, L2, L--4, TR4, still, U, iidDI, QRU, L3. Theenergized relay U closes its contacts UI, U2, U3 and U4. The closedcontacts U 1 provide a self holding circuit for the contactc-r U. Theclosed contacts UI, U2 and U3 connect the motor 80 to the supplyconductors I, II and III and thereby energize that motor through itsresistors TI, T2 and 1'3 to start operation for opening the enginevalves.

The energization of the circuits to the motor 17 80 energizes therunning relay SR which closes its contacts SRI and SR2, therebyenergizing the motor contactor 6 and the shorting relay TR by thecircuit, L2, I RU, 80U4, SR2, 6 and TR in parallel, L3.

The energized relay 6 closes its contacts 6-I,

62, 6-3 and opens its contacts 6-4. The closed contacts 6-I, 62 and 63connect the motor 8| for operation and inasmuch as it is mounted on thesame shaft as the motor 80, it adds its power to that of the motor 80for rotating the shaft 63-. The open contacts 6-4 open the startingcircuit for the relay U, but that relay remains energized because it isconnected to the conductor L+I through the contacts 2RU and U4.

The energized relay TR closes its contacts TRI, TR2 and TR3 and opensits contacts TR4. The closed contacts TRI, TR2 and TR3 short out theresistors rI T2 and r3 thus increasing the strength of the motor 80. Theopening of the contacts TR I in the already open starting circuit of thecontactor U has no effect.

The energization of the motor 80 also energizes the coil 2 I 2 (Fig. 20)of the electromagnetic brake (Figs. 10 and 11) and thus raises itsarmature 209 which pulls upward on the link 208 to operate the lever 206and thereby pull the wedge 200 downwardly between the outer ends of thebrake levers I9I and I92. The downward movement of the wedge 200releases the brake arms from the brake drum and leaves the operatingshaft I60 free to rotate, thereby freeing the gearing mechanism 8'! forrotation.

The energized motors 80 and BI rotate their shaft 96 (Fig. 9) andthereby operate the gears 9I, 92, 94 and 95 to rotate the valve shaft63.

Inasmuch as the plunger is standing at the end of its rearward stroke,the gear rack II2, the gear wheel III, and the nut member IOI of thedifferential are stationary. As the motors rotate the valve shaft 63 forup direction operation, its screw-threaded portion I06 (Fig. 17) rotatesin the nut IOI which pulls the shaft axially to the left, thus movingthe main piston valve 60 from its central position in the valve chamber(Figs. 5 and 6) toward the exhaust port 44 (Fig. '7) thus opening thevalve ports 64c and permitting oil to flow through the high pressureport 43, the valve chamber section 64a, the ports 64c and the cylinderport 62 into the engine cylinder 34.

The movement of the main valve 60 operates the lever I1 to open theleveling valve in accordance with the opening movement of the mainvalve.

As the oil enters the cylinder from the pressure side of the system, theplunger starts on its forward stroke and, in doing so, moves the rackgear I I2 and thereby rotates the gear I I I mounted on the shaft I08,which, in turn, rotates the gear wheels I03 and I02 and the nut MI. Therotation of the nut on the screw threaded portion I06 of the valve shaftis in the same direction as the rotation of the valve shaft; and,therefore, due to the differential action of the screw and nut, thevalve shaft starts to slow up its axial movement when rotation of thenut begins.

As the plunger speeds up thus increasing the speed of the upwardmovement of the elevator platform, the speeds of rotation of the nut IOIand the valve shaft screw I06 approach each other. At the rate ofplatform speed for which the apparatus is designed, the speed of theplunger and the valve shaft will be equal.

Should the motors 00 and BI open the valve too far, the platform andplunger overspeed thus rotating the nut IOI ahead of the screw topartially close the valve for slowing down the platform and the plunger.As soon as the screw I06 and the nut IOI reach the same speed, theplatform has a uniform speed which is a function of the motor speed.Should there be any tendency to slight hunting, the opposing influencesaffecting the extent of valve opening rapidly come into balancedrelation such that the valve is positioned for a plunger speed turningthe nut IOI at the same rotational speed as the screw I06 is rotated bythe motor or motors.

As the elevator approaches to within approximately forty inches of theflight deck, the slowdown cam I30 engages the roller I29 to close thevalves, the cam I8I opens the initial up limit switch IRU and the camI540. is engaged by the cam lock mechanism I4Ia associated with the camI30 and forces it into locking engagement to lock the cam I30 in theposition best suited to the operation of the T-lever considering theloading on the elevator and the viscosity of the oil for operating theengine and results produced thereby on the position of the T-lever asthe cam I30 engages it.

The opening of the initial up limit switch IRU deenergizes the motorcontactor 6 and the shorting relay TR. The deenergized contactor 6 opensits contacts 6I, 6-2 and 6-3 and thereby deenergizes the valve motor 8|.The deenergized relay TR opens its contacts TRI, TR2 and TR3, therebyreinserting the resistors rI, T2 and T3 in the circuit of the valvemotor 80. The deenergi- 'zation of the motor 0| and the decreasedenergization of the motor provide for reduced torque exerted on thevalve shaft 63.

As the plunger continues toward the end of its forward stroke the camI30 raises the arm I28 of the T-lever and thereby forces its arm I33 tothe right (Fig. 13) thus moving the coupling I8 and hence the valveshaft 63 to the right and with it the leveling valve shaft I3. Theclosing movement of the main valve decreases the passage for the oilinto the engine cylinder and thereby decelerates the plunger.

When the platform is approximately thirty inches from the flight deckthe plunger cam I8I opens the follow-up limit switch 2RU but no actionfollows this because this is a safety switch designed to cause anemergency stop if the up limit switch IRU fails to disconnect the motor8| and decrease the power of the motor 80.

As the elevator platform arrives at a position within one-half inch ofthe flight deck the cam I 8I opens the final up limit switch 3RU whichdeenergizes the up direction contactor U which opens its contacts UI, U2and U3 and thereby deenergizes the valve motor 00 while it is operatingat reduced torque so that it applies no further rotative power to thevalve shaft 63. Furthermore, the deenergization of the motor 80deenergizes the brake coil 2I2, which thereupon releases the wedge 200from between the brake arms and permits the application of the brake bythe brake springs.

Returning now to the operation of the cam I30 as it is pulled under theroller I29, the movement of the cam continued to raise the arm I28 andthereby caused the depending arm I 33 to push the coupling I8 and withit the valve shaft 63 and the valve I3 to gradually decelerate theplunger to stop at the end of its forward stroke when the elevator is atthe flight deck. As this 19 decelerating action continues and T-levermoves the valve shaft 63 until the main valve gradually closes its valveports 64c and thus stops the fur-- ther flow of oil from the highpressure port 43 through the main valve ports. At the same time, themovement of the valve shaft 33 causes the lever 11 to move the levelingvalve 6! toward its closed position. However, the shape of the cam I3!)is such that in its off position for up travel, it moves the valve shaft53 far enough to cause the valve Gil to cover its ports 640 but notquite far enough to cause the leveling valve to close its ports Nb, andthe oil continues to seep through it. Hence, with the platform H)engaging the flight deck stops 19, the plunger is moved to engage thestop 41 under full pressure, due to the leakage through the exposedportion of the leveling valve permittin pressure to build up in theengine cylinder. Thus it is assured that the cables will be tensioned toexert upward force of the platform against its stops to the desiredextent.

It should also be noted that the lever 11 provides such relativemovement ranges of the main and leveling valves and that the relativelaps of the latter are such that the leveling valve closes slowly andtrails the main valve and thereby provides a Vernier-like action forsecuring a particularly fine degree of deceleration at the end of the upstroke.

Assuming now that the elevator platform is at the flight deck and thatthe attendant presses the down button DB for causing the elevatorplatform to return to the main deck, operation of the button DBenergizes the down direction relay 80D by the circuit L2, DB, 86D, 80U2,3RD, L3.

The energized relay 39D opens its contacts BODI and closes its contactsBODZ, 8ilD3 and MBA. The closing of the contacts 80D3 completes a selfholding circuit for the relay 831). The closing of the contacts 83D4prepares one part of the circuit for the relays B and TR. The closing ofthe contacts 86D2 energizes the down direction contactor D by thecircuit L2, 54, TRG, 80D2, D, 80U2, 3RD, L3. fhe energized contactor Dcloses its contacts DI D2, D3 and D4. The closed contacts D4 complete aself holding circuit for the relay D. The closed contacts DI, D2 and D3energize the valve motor 80 through its resistors RI R2 and R3.

As before, energization of the motor 80 energizes the brake coil 21;! torelease the brake 199 in the hand drive station. The energization of themotor 80 also energizes the running relay SR, which closes its contactsSR: and SR2, thereby energizing the contactor B and the shorting relayTR by the circuit L2, BED-'1, SR1, 1RD, 6 and TB in parallel, L3. Theenergized contactor 6 closes its contacts 6--l, 6-4 and 6-3 and therebyenergizes the valve motor 8| to assist the valve motor 80 in rotatingthe valve shaft for down operation. The energized shorting relay TRcloses its contacts TRI, TRZ and PR3 and thereby short circuits theresistors ri, 9'2 and T3 in the circuit of the motor 80 to thereby bringthe motor speed up to its maximum value in rotating the shaft 53.

The energized motors 33 and 8! now rotate the valve shaft 63 in areverse direction through the medium of the reducing gearing mechanismBl (previously described); and, inasmuch as the plunger is standingstill at the end of its forward stroke, the nut IUI of the differentialis standing still. Therefore rotation of the valve shaft 63 in thedifferential moves the shaft to the right and thereby causes the valveto move toward the 20 port 43 and thereby open the ports 640, thuspermitting the oil in the cylinder to flow out through the cylinder port62, the ports 64c and the chamber section are into the low pressure port44 under the pressure exerted upon the plunger by the weight of theelevator platform.

The opening movement of the valve for down operation will continue whilethe plunger starts moving and operatin the rack rail H2, thus rotatingthe gear Hi to cause rotation of the nut IQ] for down directionoperation. As the plunger gains in speed, the speed of rotation of thenut lfil increases until it is the same as the speed of rotation of thevalve shaft and the further opening movement of the valve shaft 83. Asbefore, should there be any tendency to slight hunting, the opposinginfluences affecting the extent cf valve opening rapidly come intobalanced relation such that the valve is positioned for a plunger speedturning the nut ifil at the same rotational speed as the screw ice isrotated by the motors.

As the elevator descends to within forty inches of the main deck, thecam i8! opens the first down limit switch 1RD and as the cam I I1 comesunder the roller 23 0f the T-lever, it starts to raise that lever toclose the valve for the down stop. Furthermore, the movement of theplunger carries the cam lever i5! underneath the fixed cam I5 1, thuscausing operation of the lever I51 to move the locking latch I43inwardly to lock the cam l i? in the position in which the position ofthe T-lever has forced it as they engage, the operation and reasonstherefor having already been described in connection with the cam I30.Therefore, regardless of the exact position of the arm I24 immediatelyafter it is contacted by the cam Hi, the cam will be locked in thatposition so that its free end will not move any lower but will remainwhere it is and its upper surface will serve to raise the T-arm lever124 at the desired rate for closing engine valves as the plunger movesinto its rearward position with the elevator reaching the main deck.

When the cam lSl opened the limit switch IRD that limit switchdeenergized the motor contactor 6 to deenergize the valve motor 8|. Theopened switch iRD also deenergized the shorting relay TR which openedits contacts TRI, TR2 and TBS and thereby reinserted the resistors Ti,1'! and 13 in the circuit of the motor so that the power of the motor 8don the valve shaft 63 is decreased to a small amount.

As the plunger continues to the end of its rearward stroke itsuccessively opens the limit switch 2RD and 3RD to deenergize thecontrol contactor and the valve motors in the same manner as previouslyexplained at the end of the forward stroke of the plunger.

As the plunger nears the end of its rearward stroke the shape of the camIll so operates the T-lever that it forces the valve shaft 63 to thepoint where the main valve closes the valve port 540 and at the sametime the valve shaft 63 causes the lever ll to move the leveling valvetoward its closed position, but, because of the shape of the cam I I1,it does not force the valve levers to quite close the leveling valve.Depending on the shape of the cam, the motor shaft may slow down, maystop dead, or may even be reversed during this operation.

The gradual closing Of the ports 640 by the main valve and the port 14bby the leveling valve re duces the rate of exhausting the oil and thusslows down the platform. Finally the plunger strikes its rearward stopblock (Fig. 2) but the leveling valve does not fully close with theresult that liquid leaks out of the cylinder until the pressure equalsthat of the low pressure side of the system. Consequently, aconsiderable part of the platform weight and load will press the plungeragainst its rearward stop and thus hold the platform firmly at the maindeck.

The foregoing operations describe how the pressing of an up push buttonwill cause the hydraulic engine to mOVe the elevator from the main deckto the plate deck and, also, how the pressing of the down push buttonwill cause the hydraulic engine to move the elevator from the flightdeck down to the main deck and stop it thereat.

In case of an emergency while the motor control system is being used foroperating the elevator, the elevator may be stopped by pressing theemergency stop button SB. Assuming that this button is pressed for anemergency stop, it deenergizes the circuit for the direction contactorsregardless of the direction of operation. The deenergization of eitherdirection contactor U or D deenergizes the valve motors 66 and 8| andalso the brake I99, so that rotation of the valve shaft 63 by the motorsis stopped. Meanwhile, the plunger in the cylinder continues itsmovement for a short distance and this movement operates the gear rackII2 to rotate the gear III on the shaft I98 (Fig. 17) which in turnoperates the gear wheels I63 and I92 to rotate the nut IOI on the screwI06.

Inasmuch as the shaft 63 is prevented from rotation, the rotation of thenut II will move the shaft 63 axially until it causes the main valve 69to close its ports 640. The main valve 66 will close before the levelingvalve 6I closes and oil will continue to seep through the port 1422until the operation of the differential by the plunger moves the valve66 and the valve 6| to their dead center position. In this position, theports 14b and 640 will be completely closed and no oil can flow into orout of the engine cylinder 34. Hence, with the valves on dead center,the plunger will stop moving and thereby bring the elevator platform toa stop.

It will be assumed now that the attendant desires to move the elevatorby the hand control I59 instead of by the push-button control. In orderto accomplish this, the attendant turns the handle I15 on the handcontrol and opens the cover I12. The opening of the cover I12 pushes thelink I11 to the right (Figs. 10 and 11) thereby operating the lever I18to push the slida-ble rotatable shaft I65 to the left. This movement ofthe shaft I65 meshes the gear wheel I64 with the gear wheel I63, movesthe switch arm I85 to the left to open the interlocking switch I86 inthe push-button control system, and moves the hand wheel I66 with itscrank I68 into open position on the side of the hand control casing.

The attendant then moves the crank arm I61 to its open position wherethe snap latch I18 engages the hand wheel I66 and holds the crank arm incranking position. The opening of the switch I86 opens the controlcircuit (Fig. 20) so that the push-button control system cannot be usedwhile the hand drive is in operation.

The opening movement of the cover I12 in moving the link I11 also causesthat link to engage the lost motion connection 2I5 on the arm 2 I4 ofthe crank lever 296 and thereby move that lever in counterclockwisedirection which pulls downwardly on the shaft 204 and thereby moves thebrake wedge 283 in between the outer ends of the brake arms I9I and I92,This operation of the brake wedge frees the brake arms from the brakedrum I94 so that the gear I63 and the shaft I69 may be operated byrotation of the crank arm I61. Thus, it will be apparent that theopening of the hand-drive cover I12 not only opens the interlock in theelectric control system but also releases the brake I99 from holding theshaft I60 and, consequently, the valve shaft 63 against rotation.

It will be assumed now that the attendant grasps the crank handle I 68and rotates the crank arm I61 in the correct direction for moving theelevator in the direction he wishes it to move. This rotation of thecrank shaft rotates the shaft I65 and with it the gear I64 in mesh withthe gear I63, and thereby rotates the operating shaft I66 so that thegear wheel I6I on the lower end of the shaft in mesh with the gear I62on the shaft 93 rotates the pinion 94, the gear wheel 95, and with itthe shaft 63. The rotation of the shaft 63 in the differential 83 willcause it to move axially in accordance with the direction in which theelevator is to be moved in the same manner as when the valve shaft 63was operated by the electric motors and BI.

Inasmuch as the rotation of the valve shaft 63 and the differential isthe cause of moving it axially, it will be apparent that the crank armI61 must be turned constantly to keep the elevator in movement. Ofcourse the differential will be moved to some extent by the operation ofthe rack gear II2 on the plunger but not enough to noticeably affect theaxial movement of the gear shaft 63. Inasmuch as the gear shaft 63 mustbe rotated by the hand device in order to move it axially, this adds asafety element for hand operation, because stopping the hand rotation ofthe hand drive crank will immediately stop the elevator. The handoperation drive may drive the elevator as fast as the motor controldrive does, but experience shows it is difficult to continue this speed.A slower turning of the hand wheel will yield say half speed. A veryslow turning will provide an inching speed for fine adjustment, and forinching purposes during a stowing or other operation of the elevatorplatform. The hand drive may be used at any time for normal operatingpurposes, if the motors fail or the electric power is shut off so thatthe electric drive cannot be used.

In the modified form of my invention illustrated in Fig. 22, I haveillustrated a modification of my invention in which the valve shaft 63aas operated to control an inlet port 432) and an outlet port 442) forcontrolling a hydraulic engine (not shown) such as the engine I8 foroperating an elevator platform lila by a plurality of hoisting cablesI60. and Ma.

The valve shaft is controlled by a constant speed electric motor 80a, adifferential mechanism 83a and a pair of stop cams HM and I39a. Themotor is connected to the shaft by a gear reducing mechanism 81a and aflexible coupling d. The diiferential comprises a nut IOIc disposed on ascrew portion lfl6a of the shaft and operated by a gear rack II2aattached to the elevator platform. Suitable collars I04a and I05a aremounted at the ends of the nut I6 Ic to prevent axial movement thereof.The cams Illa and I30a are mounted on a shaft 2I1 attached to theelevator platform.

When the platform is to be moved, the motor 80a is energized to rotatethe shaft 53a in the nut

